On the back of your card, look on the signature line. You will see part or
all of your card number printed there. After the card number, there will be
some additional numbers. This is your card security code.

American Express

On the front of your card, look just above and to the right of the card number.
You will see several numbers that are NOT raised. This is your card security
code.

Discover Card

On the back of your card, look on the signature line. You will see part or
all of your card number printed there. After the card number, there will be
some additional numbers. This is your card security code.